APPLICATION OF UNMANNED AERIAL PHOTOGRAPHY FOR THE ESTIMATION OF EXTRACTED ROCKS AT BEAUTIFUL ROCK QUARRY, LOKOJA, NIGERIA

Abstract

This research was carried out to investigate the application of unmanned aerial photography for the estimation of extracted rocks at Beautiful Rock Quarry, Lokoja, Nigeria. This research addresses the challenges of inadequate mine production planning between the government regulatory agency and the mine operators on the issue of monthly production rates/returns, taxes and royalties. It also fills an information gap by creating a database platform for an avenue to make a timely decision at managerial level for the mine operators and regulators. To achieve the aim of the research, 2D and 3D models for the Mined out Pit and Stockpile were computed. The geometry properties of the Mined out Pit and Stockpile were generated. Also, the tonnage of the Mined out Pit and the Stockpile were correlated. The aerial views of the 2D images captured were used to generate the aerial views in 3D models for the Digital Terrain Models (DTMs) and the Digital Surface Models (DSMs). Image Processing Software’s (ImageJ and Regard3D) were used for the processing of the images. ImageJ was used for Image to Stack, Stack to Montage and 3D Interactive Surface Plots; while Regard3D was used for Image Matching and Area Triangulation. Correction checks were made for the Sensor Coordinates due to tilted air photograph and the Ground Coordinates were established. The Extracted Pit and the Stockpile were analyzed using the image processing software to identity elevation spots and generate Z – Plots for the Pit and the stockpile. With the results generated from the image processing software (ImageJ and Regard3D); Area of the Pit and Tonnage of the extracted Pit were computed for the Pit to be 2,496.923 m2 and 1,027,204.512 tons respectively while the Stockpile was computed to be 44,695.39 tons. The total aggregates sold from the Quarry stood at 1,715,800 tons as at December, 2020 with an average annual production of 190,644.444 tons. The expected tonnage of the extracted rocks from the Pit after excavation and crushing into aggregates was computed to be 1,746,247.670 tons, which is about 2% (30,447.67 tons) higher than the total aggregates sold from the Quarry. This 2% is attributed to the loss in granite aggregates during production and fly rocks during blasting operations. Therefore, an allowance of approximately ±2% should be given for the expected tonnage extracted from the Pit after excavation and crushing into aggregates and the total aggregates produced from the Quarry. The difference between the computed tonnage of extracted rocks from the Pit and the total aggregates sold from the Quarry was due to Swell Factor of the rock (1.70), fly rocks during blasting operations and loss of aggregates during loading and haulage. The government agencies and the mine operators should adopt this research materials and method as a new alternative and digital method of estimation which will assist them to quantify the amount of resources extracted by the mine operators in order to determine their appropriate royalties and taxes. This research methods and design can also be used for mineral surveying and estimation when the mineral deposit is not accessible due to the rugged terrain of the area or insecurity issues. The main challenge encountered in this research was during aerial mapping due to the short battery life of the Drone which ranges from 25 to 30 minutes. The battery life of the Drone can be improved upon by the manufacturers in order to increase its effectiveness.